For basic commands, check these out

https://help.ubuntu.com/community/UsingTheTerminal

http://www.pixelbeat.org/cmdline.html

for secure shell hosting, i.e. gaining wireless access to your N900 and the Xterminal via your laptop/PC (this allows quicker input since you are using your computer to type/copy-paste to the N900) check out WinSCP http://winscp.net/eng/docs/guides and http://scratching.psybermonkey.net/2...g-openssh.html